1. Field of the Invention
The present invention relates to a method and apparatus for improving yield ratio of a testing device, and more particularly, to a method and apparatus for improving yield ratio of a testing radio frequency device.
2. Description of Related Art
Functions and electric properties of various integrated circuit chips (IC) such as radio frequency ICs, memory devices, consumer devices, logic and mixed signal ICs, image sensors and driver ICs must be tested and verified by a tester in order to insure their quality. The above-mentioned devices under test or DUTs are tested through test signals provided by the tester to verify the functions. However, DUTs are usually sensitive to high frequency electromagnetic interference, such as with radio frequency ICs, wireless LAN devices or cellular phone application devices. The testing of such radio frequency ICs, wireless LAN devices or cellular phone application devices specifically sensitive and susceptible to high frequency electromagnetic interference can result in alteration of test results. Particular instances in which high frequency electromagnetic interference can alter test results of the testing of these sensitive devices can involve the high frequency electromagnetic interference altering the judgment of the tester such that a DUT is placed in a fail bin rather than a pass bin, or vice versa, or can even result in incorrect marginal-fail decisions thus causing yield loss of testing quantity and reducing an efficiency of (e.g., wasting the time of) the work force.
In order to avoid such interference from the testing environment and resulting misjudgments of test results, the interference from a given testing environment is usually checked before testing. Uses of wireless communication equipment are restricted and other outside influences are removed or adjusted before testing. However, such acts cannot immediately resolve the problems resulting from unpredictable electromagnetic interference since the strength and influence of electromagnetic waves tend to vary with location and time. Such unpredictable electromagnetic interference problems can also introduce uncertainty as to yield loss of testing or even if there is any yield loss of testing. In such circumstances, it is hard to estimate how much yield loss of testing is caused by electromagnetic interference when electromagnetic interference is present and to timely exclude the electromagnetic interference. Since yield loss of testing caused by electromagnetic interference can be difficult to estimate, yield loss recovery evaluation can also be difficult to perform.
In order to solve the above-mentioned problems, the invention provides a method and apparatus for improving yield ratio of testing devices to avoid error resulting from electromagnetic interference of the environment and timely resolve the yield loss of testing caused by unpredictable electromagnetic interferences so as to improve the efficiency and yield ratio of testing and decrease the cost of testing.